The present invention relates to a pneumatic tire, more particularly to a tread pattern capable of improving the wet performance and noise performance in a well balanced manner while maintaining the steering stability.
Heretofore, it has been known to be effective for improving the steering stability on dry roads to increase the rigidity of the land portions (or ground contacting tread elements) by increasing the land ratio of the tread portion (proportion of the total area of the land portions to the overall tread area) as far as possible.
In the case of pneumatic tires designed for large-sized passenger cars having heavy weight, since the ground pressure of the tread portion becomes large, it is especially effective to increase the land ratio by decreasing the total volume of tread grooves.
In recent years, on the other hand, on the outside and inside of the passenger cars, quietness is sought, therefore, a tire is also required to reduce its noise during running. For example, the so called air resonance sound and air pumping sound which occur in tread grooves in the ground contacting patch and become main causes for the pass-by noise, can be reduced by decreasing the volume of the tread grooves.
However, if the volume of the tread groove is decreased, wet performance of the tire is liable to deteriorate. Particularly, if the groove volume is decreased in the tread central region, hydroplaning phenomenon is more likely to occur.